The petroleum industry is increasingly turning to heavy crudes, resids, coals and tar sands as sources for feedstocks. Feedstocks derived from these heavy materials contain more sulfur and nitrogen than feedstocks derived from more conventional crude oils, requiring a considerable amount of upgrading in order to obtain usable products therefrom. The upgrading or refining is accomplished by hydroprocessing processes, i.e., treating with hydrogen of various hydrocarbon fractions, or whole heavy feeds, or feedstocks, in the presence of hydrotreating catalysts to effect conversion of at least a portion of the feeds, or feedstocks to lower molecular weight hydrocarbons, or to effect the removal of unwanted components, or compounds, or their conversion to innocuous or less undesirable compounds.
Catalysts commonly used for these hydroprocessing reactions include materials such as cobalt molybdate on alumina, nickel on alumina, cobalt molybdate promoted with nickel, nickel tungstate, etc. U.S. Pat. Nos. 4,824,821 and 5,484,755 and US Patent Publication No. 2006/0054535 disclose hydroprocessing catalysts in the form of high activity slurry. The catalyst is produced from Group VIB metal compounds by sulfiding an aqueous mixture of the metal compounds with hydrogen sulfide (H2S) gas at a pressure of up to 5,000 psi (340 atm). U.S. Pat. Nos. 7,754,645 and 7,410,928 discloses a hydroprocessing catalyst and methods for making the catalysts, by reacting at least a Group VIB metal compound with a Promoter metal compound, sulfiding the intermediate mixture with a sulfiding agent, then mixing the sulfided catalyst precursor with a hydrocarbon diluent to make a bulk slurry type catalyst.
There is still a need for improved catalysts with optimum morphology, structure and improved catalytic activity. There is also a need for improved processes to prepare catalysts for use in the conversion of heavy oils and residua.